The following snippet from Jobst Brandt in the Clincher vs. Sew-ups thread got me thinking:
<quote> What do you think that material [I take this to mean a clincher rim's extended sidewalls used to contain the tire] is not doing? The entire cross section of the rim supports spoke tension in compression as an arch and all of it is necessary. You seem to think that the rim does nothing in bending or compression while both of these characteristics are essential to a durable wheel. It is the heavy deep "V" shape of the 16-spoke aero rims that make the low spoke count possible. </quote>
Applying this notion to a non eyeleted double-wall clincher rim, how much of role would one assign to material forming the rim bed (in a plane parallel to the axle) in supporting spoke compression in comparison to the rim's sidewalls and 'V' profile (i.e., rim material along the same plane as the compressive force exerted by the spokes)?
And with higher spoke complements, the arches over which the rim must support spoke tension are shorter; wouldn't the rim require less robust construction? I'm just wondering, where it concerns your typical roadie, if there's not a spoke count beyond which the extra strength of double-wall and/or V profile rims is superfluous.
What do you think that material [I take this to mean a clincher rim's extended sidewalls used to contain the tire] is not doing? The entire cross section of the rim supports spoke tension in compression as an arch and all of it is necessary. You seem to think that the rim does nothing in bending or compression while both of these characteristics are essential to a durable wheel. It is the heavy deep "V" shape of the 16-spoke aero rims that make the low spoke count possible.
Quoted message said:
Applying this notion to a non eyeleted double-wall clincher rim, how much of role would one assign to material forming the rim bed (in a plane parallel to the axle) in supporting spoke compression in comparison to the rim's sidewalls and 'V' profile (i.e., rim material along the same plane as the compressive force exerted by the spokes)?
Consider the rim as a straight beam with a large compressive load on its end. The box shape and entire cross section is loaded in compression so that the angular orientation with respect to the axle has no effect. It is basically a pressure vessel with inward pressure on the hoop of the rim.
Quoted message said:
And with higher spoke complements, the arches over which the rim must support spoke tension are shorter; wouldn't the rim require less robust construction? I'm just wondering, where it concerns your typical roadie, if there's not a spoke count beyond which the extra strength of double-wall and/or V profile rims is superfluous.
The arch supports loads in compression. That is why old stone bridges, without mortar, use arches to support great loads. Bending is local to the spoke socket and only becomes a problem with to great a concentrated load caused by widely spaced (few) spokes. The main stress is compression.
The deep "V" serves a dual purpose. It helps span the spoke gaps and increases lateral bending stiffness especially for alternately spoked wheels with <20 spokes where alternate spoking would possibly cause lateral waves in the rim.
The deep "V" serves a dual purpose. It helps span the spoke gaps and increases lateral bending stiffness especially for alternately spoked wheels with <20 spokes where alternate spoking would possibly cause lateral waves in the rim.
As Henry Higgins said, "I think (s)he's got it, I think (s)he's got it!"
The deep "V" serves a dual purpose. It helps span the spoke gaps and increases lateral bending stiffness especially for alternately spoked wheels with <20 spokes where alternate spoking would possibly cause lateral waves in the rim.
As Henry Higgins said, "I think (s)he's got it, I think (s)he's got it!"
As Eliza said: "Ooh, 'Enry 'Iggins, you 'orrible man!"
